You are looking for this option in GUI. Device & Media => Device Properties.
When I say "Offline Restore" I mean it from an EADR perspective. Here is a section from DisasterRecovery.pdf.
Note that Data Protector first tries to perform an online restore. If the online restore fails for
any reason (for example, the Cell Manager or network service is not available or firewall is
preventing access to the Cell Manager) Data Protector tries to perform remote offline recovery. If
the remote offline restore fails (for example, because the Media Agent host accepts requests only
from the Cell Manager), Data Protector performs a local offline restore.
Please use the Accept Solution button next to my post and assign a KUDO (thumbs up icon) if this works for you.
Regards,
Sebastian Koehler